Knockdown ventless shallow sheetmetal fireplace firebox

ABSTRACT

In accordance with the present invention a knockdown ventless sheetmetal fireplace firebox that is simple and inexpensive to manufacture, easy to assemble, and is less than 10″ in exterior depth.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND OF THE INVENTION

In woodburning fireplaces the area where the fire burns, called the firebox, has historically been made out of brick or similar material and has been built into the house structure. Such fireboxes are usually over 12″ in interior depth so that they can hold several wood logs. They also require venting for smoke.

More recently, factory built fireboxes made out of sheetmetal and attached to a house structure have become popular. An example of such a sheetmetal firebox used in a woodburning fireplace is shown by Bailey and Howell in U.S. Pat. No. 4,700,687. Such fireboxes usually have an exterior depth, before attachment to the house structure, of 15″ so they have enough room for an insulation system and a plurality of burning logs in the combustion area. They also require venting for smoke.

As gas fireplaces using gas burners and artificial logs became popular sheetmetal fireboxes for such fireplaces have also been offered. Some require venting and some do not. Similar to sheetmetal fireboxes meant to hold burning wood, gas fireboxes can be attached to a house structure. Two examples of sheetmetal fireboxes used in a gas fireplace are shown by Valters and O'Hearn in U.S. Pat. No. 6,116,232, and Wade, in U.S. Pat. No. 5,901,701. Such fireboxes are usually over 15″ in exterior depth.

As explained by Wade in U.S. Pat. No. 5,901,701, sheetmetal fireboxes can be large and expensive to manufacture because they frequently require layers of steel welded to each other and separated by air gaps or insulation. This “box within a box” layout is how many fireboxes contain the heat generated by the fire. As Wade explains, this is required because traditional fireplaces can generate as much as 40,000 BTU's of heat. Some can generate more.

Wade's firebox is not a knockdown design, i.e., a design that can be assembled by a consumer. Similar to other prefabricated fireboxes, it requires large amounts of storage space when held in a warehouse prior to sale and it does not offer the cost savings that consumers can prefer when they assemble an item themselves.

The present invention is a knockdown, ventless, cartridge fireplace firebox that is easy to assemble, inexpensive to produce and consists of five (5) sheetmetal pieces screwed together. The firebox holds a noncombustible, imitation log which itself surrounds a smokeless, rectangular, alcohol gel fuel cartridge of the type generally described in U.S. application Ser. No. 11/090,937. Because the rectangular fuel cartridge does not produce smoke, the firebox can be inserted into a freestanding mantle which may be placed a room without being connected to a chimney or any venting system whatsoever.

Because the fuel cartridge described in U.S. application Ser. No. 11/090,937 is rectangular and substantially hidden inside an imitation log that is also somewhat rectangular, i.e., wider than it is deep, the way real fireplace logs are shaped, the cartridge system produces a visually appealing fire that simulates a real wood fire. At the same time, however, the rectangular fuel cartridge only produces about 5,000 BTU's of heat. Because so little heat is produced the firebox invention disclosed here does not require an extensive insulation system, making it dissimilar to traditional sheetmetal fireboxes.

Additionally, because the cartridge itself may be less than 3″ in depth and because the system does not require a gas burner or space for numerous logs, and because it does not require a “box within a box” structure or an extensive insulation system, this firebox can be extremely shallow, for example, less than 10″.

DISADVANTAGES COMMON TO THE PRIOR ART

The applicant is unaware of any knockdown, ventless, shallow, sheetmetal, cartridge fireplace fireboxes that take advantage of the burner system described by this inventor in U.S. patent application Ser. No. 11/099,937.

Buffington, in U.S. Pat. No. 7,140,364 B1 discloses a prefabricated modular fireplace with a lightweight, vermiculate concrete firebox. Unlike applicant's invention, Buffington's invention is not ventless, is not sheetmetal and is not designed to work with cartridges.

Hussong, in U.S. Pat. No. 5,738,084, discloses a ventless patio fireplace fueled by gas. Unlike applicant's invention, Hussong's invention is not knockdown and does not work with a gel fuel cartridge.

Meyers, in U.S. Pat. No. 4,573,905, discloses a ventless burner unit for fireplace simulation that uses glass and lights to produce the sensorial effects of a fire in a traditional fireplace, but Meyers' invention is not a knockdown firebox that uses rectangular cartridges. Similarly, in U.S. Pat. No. 4,890,600, Myers discloses a fireplace simulator unit that may or may not be vented, but this invention is not a simple knockdown unit and also does not use rectangular cartridges.

Fischer, in U.S. Pat. No. 4,838,781, discloses a ventless fireplace insert that uses multiple round cans of fuel. Unlike applicant's invention, Fischer's invention is not a knockdown firebox and it does not use a cartridge.

Fortier, in U.S. Pat. No. 4,127,099 discloses a stove and grill device which utilizes a knockdown design, but Fischer's invention is not a fireplace firebox that can be inserted into a fireplace mantel nor does it use a fuel cartridge.

Hodge, et al., in U.S. Pat. No. 6,024,085, discloses a modular fireplace but this invention requires a modular chimney, is not a firebox, is not ventless, and does not use a knockdown design.

Sulak, in U.S. Pat. No. 6,178,965 B1, discloses a stowable fireplace which is not ventless and burns wood versus an alcohol gel cartridge.

Wade, in U.S. Pat. No. 5,901,701, discloses an unvented complete fireplace made of sheetmetal, but this invention is not a firebox, is not fueled by gel alcohol cartridges and does not use a knockdown design.

Facchina, in U.S. Pat. No. 5,794,610, discloses a free standing ventless unit but Facchina's invention is not a sheetmetal firebox, but rather an entire fireplace including the mantle, and this invention is not designed to burn alcohol gel cartridges.

OBJECTS AND ADVANTAGES

The objects and advantages of the invention described herein are to provide a fireplace firebox that:

-   (a) does not require ventilation, -   (b) can be manufactured out of five pieces of sheetmetal, -   (c) can be sold as a “knockdown” unit assembled by a consumer, -   (d) has an extremely shallow exterior depth, i.e., less than 10″, -   (e) does not have to be insulated, and -   (f) is capable of being inserted into any style fireplace mantle,     including those made of wood or stone, whether they encompass a     traditional or modern design.

SUMMARY

In accordance with the present invention there is provided a knockdown, ventless, shallow, sheetmetal fireplace firebox that is simple and inexpensive to manufacture, easy to assemble, and can be inserted in any style mantel.

DRAWINGS—FIGURES

FIG. 1 shows the invention.

FIG. 1A shows the bottom piece 4 of the invention attached to a fireplace mantel, which is not part of the invention but is shown for illustrative purposes only. This figure shows an air gap between the mantel and the left, right and top of the invention.

FIG. 2 shows the individual sheetmetal pieces of the invention.

FIG. 3 shows an alternative embodiment.

FIG. 4 shows another alternative embodiment.

DRAWINGS—REFERENCE NUMERALS

-   1 Invention -   1B Fireplace Mantel -   2 Left Piece -   2A Left Front -   2B Left Side -   2C Left Back -   3 Right Piece -   3A Left Front -   3B Left Side -   3C Left Back -   4 Bottom Piece -   4A Bottom Floor -   4B Bottom Front -   4C Bottom Right -   4D Bottom Back -   4E Bottom Left -   5 Top Piece -   6 Back Piece -   401-404 Insulation

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

The presently preferred embodiment of the invention is illustrated in the figures. FIG. 1 shows the invention already assembled. The black dots represent the heads of screws that are holding the invention together. The unfilled black circles represent screw holes without screws inserted in them.

FIG. 1A shows the invention screwed into a fireplace mantel 1B, which is not part of the invention but is shown for illustrative purposes only. The two lowest black dots represent the heads of screws that are holding the invention in the fireplace mantel.

FIG. 2 shows the five sheetmetal pieces comprising the invention. Left piece 2 is a single sheet of metal with two bends so as to form left front 2A, left side 2B and left back 2C. Right piece 3 is identical to left piece 2, in reverse.

Bottom piece 4 is a single sheet of metal with four sides bent at ninety degree angles to create bottom floor 4A surrounded by bottom front 4B, bottom right 4C, bottom back 4D and bottom left 4E. Welds are utilized at the four corners where 4B, 4C, 4D and 4E meet so as to form a pan structure. The exterior depth of the structure, measured substantially as the distance between bottom front 4B and bottom back 4D, is under 10″.

Top piece 5 is identical to bottom piece 4. Lastly, back piece 6 is a single sheet of flat metal without bends.

The circles in FIG. 2 represent screw holes. Broken lines indicate how screw holes align with one another. Black arrows indicate which pieces are inserted into each other for assembly.

As can be seen, left piece 2 is inserted into bottom piece 4. The bottom screw hole in left side 2B aligns with the hole in bottom left 4E. Likewise, the lower hole in 2C aligns with two screw holes, one in back piece 6 and one on the left side of bottom back 4D. Two screws, therefore, join bottom piece 4, left piece 2 and back piece 6. Likewise, two screws join bottom piece 4, right piece 3 and back piece 6.

An identical set of screw holes and screws joins top piece 5 to three pieces: left piece 2, right piece 3 and back piece 6. A total of eight screws, therefore, holds the entire assembly together.

Because left piece 2 is identical to right piece 3 and bottom piece 4 is identical to top piece 5, only three shapes of metal that have to be manufactured, thereby allowing great efficiency in the manufacturing process.

The screw holes in bottom floor 4A and the corresponding holes in top piece 5 may be used to attach the invention into a fireplace mantel.

Alternative Embodiments

An alternative embodiment is shown in FIG. 3 wherein the left back 2C and right back 3C meet one another, thereby removing the need for separate back piece 6.

Another alternative embodiment is shown in FIG. 4 wherein insulation, such as 1″ thick mineral wool or fiberglass, is represented by pieces 401-404. Although insulation is not needed to use the invention, if the back, sides, or top of the invention is placed in direct contact with combustibles, such as wood framing, insulation may be used. Such insulation may be attached using screws, adhesives, insulation hangers, etc., as is well known in the fastener and insulation fields.

Because the fuel cartridge used with this invention is under 3″ in depth and the imitation log it sits in may be approximately 6″ in depth, the distance between bottom front 4B and bottom back 4D may still be under 9″. Hence, even when 1″ thick insulation is added onto this invention its overall exterior depth may still be under 10″. 

1. A knockdown, ventless, shallow, fireplace firebox comprising of five pieces of sheetmetal, a top piece, a bottom piece, a left piece, a right piece and a back piece, where the exterior depth of the assembled unit is under 10″.
 2. A knockdown, ventless, shallow, fireplace firebox according to claim 1 wherein the five pieces of sheetmetal are held together by eight screws.
 3. A knockdown, ventless, shallow, fireplace firebox comprising of four pieces of sheetmetal, a top piece, a bottom piece, a left piece and a right piece, where the exterior depth of the assembled unit is under 10″.
 4. A knockdown, ventless, shallow, fireplace firebox according to claim 3 wherein the five pieces of sheetmetal are held together by eight screws.
 5. A knockdown, ventless, shallow, fireplace firebox according to claim 1 wherein the left and right pieces are identical and the top and bottom pieces are identical.
 6. A knockdown, ventless, shallow, fireplace firebox according to claim 5 wherein the five pieces of sheetmetal are held together by eight screws.
 7. A knockdown, ventless, shallow, fireplace firebox according to claim 3 wherein the left and right pieces are identical and the top and bottom pieces are identical.
 8. A knockdown, ventless, shallow, fireplace firebox according to claim 7 wherein the four pieces of sheetmetal are held together by eight screws.
 9. A knockdown, ventless, shallow, fireplace firebox according to claim 1 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 10. A knockdown, ventless, shallow, fireplace firebox according to claim 2 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 11. A knockdown, ventless, shallow, fireplace firebox according to claim 3 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 12. A knockdown, ventless, shallow, fireplace firebox according to claim 4 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 13. A knockdown, ventless, shallow, fireplace firebox according to claim 5 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 14. A knockdown, ventless, shallow, fireplace firebox according to claim 6 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 15. A knockdown, ventless, shallow, fireplace firebox according to claim 7 wherein insulation is attached to the exterior of the left, right, top and back of the invention.
 16. A knockdown, ventless, shallow, fireplace firebox according to claim 8 wherein insulation is attached to the exterior of the left, right, top and back of the invention. 